Apparatus for the manufacture of contoured asbestos sheet

ABSTRACT

A corrugated asbestos cement forming machine including a flat horizontally-movable table having flexible resilient membrane sections as well as rigid portions is provided to accept a flat wet asbestos cement sheet. Such sheet is placed upon the entire table and as the edges of the separate flexible membrane sections are urged together in an accordian fashion, the membrane sags and thereafter gravity causes the wet asbestos cement sheet to assume the shape and contour developed by the sagging flexible membrane. Rigid support members beneath the flexible membrane sections assure the desired contour of the asbestos cement sheet.

United States Patent [191 Schulte APPARATUS FOR THE MANUFACTURE OF CONTOURED ASBESTOS SHEET [75] Inventor: Joseph B. Schulte, St. Louis, Mo. [73] Assignee: GAF Corporation, New York, NY.

[22] Filed: Aug. 9, 1971 [21] Appl. No.: 169,948

FOREIGN PATENTS OR APPLICATIONS Great Britain 264/286 Oct. 9, 1973 Primary ExaminerRobert L. Spicer, Jr. Att0mey-Wa1ter C. Kehm et a1.

[5 7] ABSTRACT A corrugated asbestos cement forming machine including a flat horizontally-movable table having flexible resilient membrane sections as well as rigid portions is provided to accept a flat wet asbestos cement sheet. Such sheet is placed upon the entire table and as the edges of the separate flexible membrane sections are urged together in an accordian fashion, the membrane sags and thereafter gravity causes the wet asbestos cement sheet to assume the shape and contour developed by the sagging flexible membrane. Rigid support members beneath the flexible membrane sections assure the desired contour of the asbestos cement sheet.

3 Claims, 3 Drawing Figures APPARATUS FOR THE MANUFACTURE OF CONTOURED ASBESTOS SHEET This invention relates to a method and apparatus for forming corrugations in flat, uncured asbestos cement sheets.

More specifically, the invention relates to an apparatus for the manufacture of corrugated sheets from asbestos cement sheets or other plastic material that includes moldable sheet material containing fibers and hardening agents.

Up until the development of the present invention, several different methods and apparatuses for forming corrugations in flat sheets have been employed. The use of bars, narrow belts, or vacuum assemblies to force the sheets into the desired shape have been employed and had certain drawbacks. In particular, the aforementioned were not found to be well suited for forming large and deep corrugations, such as was used in the manufacture of canal bulkhead sheets.

In better understanding the present invention, a consideration of the prior art is important. For an example, U.S. Pat. No. 2,589,379 relates to a process making use of an approach in which moldable sheet is formed at definitely spaced intervals while being subjected to the action of suction chambers. The flat sheets are arranged in a manner wherein the suction chambers grip the sheets and fold them into corrugations of the desired width and depth. A particular drawback associated with this method relates to the quality of product produced, particularly cracks which may ultimately rupture which cracks are formed because there is an uneven rate of forming or stress in the sheet while it is being formed. The apparatus, according to this reference is quite complicated and more imporatant quite expensive to construct and operate.

In some vacuum forming systems, the contoured box or frame is not movable. The sheet is supported on a muslin membrane which is kept taut by means of rollers on either side of the machine. The flat sheet is deposited on the muslin and then a vacuum is applied and timed to draw the sheet as well as the muslin into a lower position. Hence the sheet is free to slide.

Furthermore, this process is quite complicated and requires a greater degree of captial expenditure than the present invention. Another system employing the vacuum is somewhat similar in configuration to the present invention except that instead of gravity acting upon the sheet in the formation of the contours, a vacuum is drawn as the parts are moved together. As a result of this process, loss of time and non-uniformity takes place because the sheet is under stress. The present invention provides a simple and yet infinitely better approach to the formation of the contours.

U.S. Pat. No. 2,593,61 1 relates to still another technique employed in forming corrugated sheet. This approach consists of an arrangement in which the sheets are carried through the assembly line by means of conveyors (V-belts). As the different operations are performed on the sheet material, conveyor belts transport the product from one station to the other. This apparatus is intended to work limited runs of output into corrugated sheets. Such prior art reference calls for alternative branches of conveyor lines for causing the sheets to travel from a single forming machine along to the desired stages in production.

The principal object of the present invention is to provide a simple and inexpensive method and apparatus for the manufacture of contoured products such as canal bulkhead material.

Another object of the present invention is to provide an apparatus for the manufacture of canal bulkhead material which is highly efficient providing a finished end product free from physical defects lines of stress, etc.

Another object of the present invention is to provide an apparatus having a small number of moving and operative parts enabling it to have a long machine life. A further object is to provide an apparatus for the manufacture of canal bulkhead material having a high degree of power efficiency.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which: 1

FIG. 1 is a perspective view of the working members employed in the present invention in which the support members are in the open or extended position.

FIG. 2 is a view similar to that of FIG. 1, except the support members and associated working parts are in the closed position.

FIG. 3 is a perspective view of the overall machinery employed in the manufacture of corrugated asbestos cement material including the present invention.

The present invention is directed to an apparatus employing principles which are more simple and more readily applicable to a high quality product as compared to the aforementioned prior art.

Briefly, the present invention is directed to an apparatus for manufacturing canal bulkhead material and the like from asbestos cement sheet material including a base, a flat movable table mounted on said base, said table being formed by a series of alternately rigid and flexible surface sections, a pneumatically-driven piston means adapted to-urge horizontal movement of said series of surface sections toward the center of said table upon a given signal; and a series of rigid contoured supports disposed beneath the plane of the top of the surface of said flexible surface sections within said supports when said flexible membranes have dropped to their lower most position beneath the surface of said table.

Furthermore, it is within the contemplation of the present invention to include a method of producing a contoured asbestos cement sheet or the like comprising the steps of placing a wet asbestos cement sheet upon the machine having a flat table surface including rigid and resilient flexible sections; pneumatically urging said table to move in a horizontal plane toward the center of said machine whereby such movement causes said resilient flexible sections to move in a downward direction; nestling said flexible sections within rigidly contoured support members disposed beneath the table surface in such a manner as to have such flexible sections conform to support member contours, simultaneously therewith said wet asbestos cement sheet material drops by gravity into the contoured shape of said flexible sections without causing any stress on said contoured sheet; lifting a finished contoured asbestos cement sheet from said forming table; and pneumatically returning said movable table to its start position.

Generally speaking, according to the present invention, a wet sheet is disposed on substantially a flat table.

The portions which are to be contoured are positioned on flexible membranes and the portions which are not to be contoured rest on rigid members. The sheet rests on the flat table with the flexible membranes consisting of several sections and as the edges of the flexible membranes are moved closer and closer together, the membranes and the sheet sag by gravity at the unsupported portions and the sheet is formed by that means with a minimum of stress. Of great importance is the fact that the sheet does not slide on the supporting membrane and therefore the sheet is not stretched. The supporting members are of a predetermined shape in accordance with the contour being formed. In addition, the gap or distance from support-member to support-member is also a factor which is taken into account when designing for a prescribed contour. Obviously, a different contour will require a different setting on the distances or gaps between supports. For any given manufacturing run, the distances are to fixed and not altered. The flexible membrane is made of a rubbery material, in this case, neoprene. For purposes discussed herein, the width of material is a 30" width but obviously not intended to be limited to function within that width. Contouring of the wet sheet, once it assumes a given crosssectional shape, causes the material to decrease in size.

In particular, the advantages of the present invention over the prior art have been found to be:

1. A controllable rate of forming asbestos cement bulkhead materials.

2. The end product is of a high quality, free from forming cracks and points of stress.

3. The operation required to produce an end product is one that does not require a high degree of skill for operating the apparatus.

4. The overall cost of the forming equipment is quite modest when compared to the prior art apparatus.

The apparatus, as such, employs techniques which make use of gravity to form the profile of the bulkhead material.

The techniques employed in the manufacture of canal bulkhead materials have been identified in great measure with the Hatschek process. In this process, sheets of material consisting mainly of a mixture of asbestos fiber, portland cement, water and other ingredients are employed to produce an end product. Typically, these sheets are produced in sizes from 4' in width by 8' to 12' in length, ranging in thickness from one-eighth of an inch to three-eighths of an inch and are quite flexible and can be shaped to a predetermined size and shape up until the cement cures or sets. The flexible-uncured flat sheets are formed into corrugated shapes by techniques which are well known to the prior art, including the processes mentioned above. The sheets, once formed into the desired length, width and thickness are then stacked on preformed steel sheets for curing the finished product.

The present invention relates to a new forming machine making use of gravity to form and shape asbestos cement material into a desired contoured cross-section. More particularly, in operation, the apparatus employs a wet uncured flat sheet of asbestos cement material deposited on a form or platen by means of a suitable device such as conveyor belt or suction lift box of the type commonly employed in the industry. At this point, the flat sheet rests on support members and sheets of suitable flexible support material such as rubber. The support members are mounted on ways and can be moved to the central line of the machine by suitable means such as hydraulic or pneumatic cylinders in combination with appropriate linkages.

A sheet is formed by moving the support members toward the center line of the sheet as it is resting on the support members. As this operation takes place, gravity causes the asbestos cement sheet and the flexible material to assume the shape of the molds which are attached to the support members. The molds are shaped and are of sufficient tolerance to permit the travel of each structural member at a precise point to select a given profile. The formed sheet is then picked up and stacked by a suitable means, such as a suction lift box that has a suction face that meets with the contour of the formed sheet. The support members are then moved outward from the center line to the original position and the machine is ready to receive another flat sheet and repeat the entire manufacturing cycle. It should be pointed out that the technology employed in the manufacture of the aforementioned canal bulkhead sheet is not limited to forming sheets for canal bulkhead material per se, nor is it intended to be limited to the profile shown. By changing the number and shape of movable members, molds and support materials and by altering the spacing and the amount of travel, other profiles may be produced. Forming machines can be made to accommodate any size sheet.

The present invention is shown in FIG. 1 in which contoured asbestos cement sheet material is formed such as has been described above. According to the invention, a flat sheet(wet) is deposited on a top surface or bed 1 which is supported on a series of structural members. A vacuum lift box (not shown) of the conventional type, is employed to place this flat wet sheet on bed 1, then the sheet is formed by keeping main base 7 stationary and urging support member assemblies 3, 4, 5 and 6 to move horizontally toward the center of bed 1. The flexible membranes 2A, 2B and 2C are supported by a series of contoured metal members 3A, 38, 4A, 4B, 4C, 41), 5A, 5B, 5C, 5D, 6A and 6B. These contoured metal members, respectively, are urged to move towards the center of the apparatus in concert with one another, by means of a pneumatic means having an intake at 10. A series of air cylinders, not shown, provide air as the prime mover which enters through intake 10 and urges shafts 8 and 9 to move in a horizontal plane towards the center position of the apparatus. This horizontal movement in turn causes the flexible membranes 2 to drop by gravity, to a level sufficient to nestle in the contoured metal members of assemblies 3, 4, 5 and 6. The lower limit of the flexible membrane, once it sags, is controlled by the length of stroke of shafts 8 and 9. The contoured supports assist in maintaining proper control over the flexible membrane as it sags and retains the flexible membranes in its final position to assure that the desired contour is being molded. The contoured support assemblies 3, 4, 5 and 6 are secured in position as part of the frame of the machine and are movable support members, whereas base 7 is stationary. The air cylinders and associated manifold govern the movement of shafts 8 and 9 and effectively control the lateral movement of contoured support members. The lateral motion is imparted to the support assemblies 8, 4, 5 and 6 as translated through shafts 8 and 9 governs the degree of sag in the flexible members 2 and this sag decreases as the gap between support members 3, 4, 5 and 6 increases and as the gap decreases the degree of sag in the flexible membranes 2 is increased. The distance between support members in effect sets the limits for flexible member sag.

Furthermore, increasing or decreasing the air pressure and rate of air flow in turn directly affects the rate of movement of the shafts 8 and 9 which in turn controls the speed of contour formation. An increase in air pressure and flow rate forces the shafts 8 and 9 to move quickly. The movement of the contoured support assemblies 3, 4, 5 and 6 takes place during an interval of time while the wet sheet being formed is on the rubber membrane. The time of movement of support members is predetermined, for an example, on the order of two to three seconds. It has been found that this interval, that is, the time elapsed from the supports being at the open or extended position to the closed position is sufficient time to enable the contours to be properly developed. The shafts 8 and 9 are merely two of a series which can function on the same line and for simplicity of explanation by only the function of 8 and 9 are being described. There are a sufficient number of support members and associated shafts and air supply to provide for uniform contour formation on the asbestos cement material.

FIG. 2 shows the asbestos cement sheet already formed on the equipment described in FIG. 1. Movable supports 3, 4, 5 and 6 have been urged by shafts 8 and 9, respectively, to move towards the center of the equipment. The movement of these supports permits the sheet to be formed by gravity. Once the support members are moved towards the center, the flexible membranes 2 are caused to droop or sag, thus permitting the wet sheet to assume the contour of the flexible membrane. The movement of contoured support assemblies 3, 4, 5 and 6 are governed by the proper linkage to shafts 8 and 9 and are arranged so that the movement of assemblies 3 and 6 is greater than that of 4 and 5.

As the support members 3, 4, 5 and 6 are urged to move towards the center, there is an excess of flexible material 2 resulting in an accordian effect permitting it to drop into the gap by the force of gravity.

The wet asbestos cement sheet 16 immediately starts to sag once the nest 17A, 17B and 17C are formed by the dropping of the flexible membrane 2 and as the bed 1 changes its shape, the wet asbestos cement material 16 follows the same contour as the flexible membrane without any slippage of the asbestos cement sheet on the bed 1. Once the sheet 16 has fallen by gravity to its low wetting position, a finished product is at hand. Thereafter, it is ready to be lifted out of the form with a conventional vacuum lift box (not shown) that has a contoured surface similar to that of the formed sheet 16. Thereafter, the shaped asbestos cement is removed and the apparatus is reactivated through its pneumatic system, as shown in FIG. 1, so that it is ready to handle the next flat sheet which is deposited and thereafter worked upon.

The apparatus will function as fast as it is possible to place a sheet upon the bed and activate the system to permit the contour to develop. The entire forming operation, on a sheet-by-sheet basis, usually takes from 2 to 3 seconds. Thereafter, the sheets are immediately ready to be lifted out with the contoured lift box and a fresh flat sheet is lifted with a flat sheet lifting box and set in place. Shafts 8 and 9 function in a manner to insure parallelism thus making certain that the contours are symetrical throughout.

FIG. 3 shows the present invention together with conventional accessory equipment utilized in the actual manufacturing operation.

Flat asbestos wet cement sheets are brought into position by a conveyor 11 where the flat sheet is picked up by a flat-faced suction box. From this point, it is transported to station 12, the gravity former, the sheet is deposited on the forming apparatus of the present invention while the support members, described above, are in the extended or open position. The system is then actuated through air cylinders to form the desired con tour on asbestos cement sheets.

After being formed, the sheet is then picked up from station 12 by a contoured suction box and is deposited on a contoured steel plate at station 14. The contoured steel plate had been previously picked up by another suction box from station 13 and deposited at station 14. This sequence is repeated through the use of the various lift boxes. Stacks of alternate steel and asbestos cement sheets are placed at station 14. The stacks of formed sheets and steel are conveyed out of the machine by a flat bed roller 15. These stacks are removed from the flatbed roller and placed in storage for curing.

In summary, according to the present invention, the finished sheet is not stretched at any point and is merely deposited on a flat surface and remains in contact with the surface throughout its forming. Other methods of manufacture, such as discussed above, require provisions for allowing the sheet to slide as it is being formed, resulting in the sheets being stressed and thereafter creating a rupture in the sheets. With the present apparatus there is no slippage.

It will be apparent to hose skilled in the art from the preceding description, that cetain changes may be made in the above apparatus without departing from the scope of the invention. It is intended that the descriptive matter above shall be interpreted as illustrative and in no way limiting, since all equivalents within the scope of the disclosure may be substituted and such substitution is intended.

What is claimed is:

1. An apparatus for manufacturing a contoured asbestos cement sheet including;

a base,

a flat, movable table mounted on said base, said table being formed by a series of alternately rigid and flexible surface sections,

a pneumatically-driven piston means adapted to urge horizontal movement of said series of surface sections toward the center of said table upon a given signal; and

a series of rigid contoured supports disposed beneath the plane of the top of the surface of said table and so positioned as to permit the nestling of said flexible surface sections within said supports when said flexible surface sections have dropped to their lower most position beneath the surface of said table.

2. An apparatus as claimed in claim 1 including;

a series of shafts driven by pneumatic means urged to move in a horizontal plane towards the center portion of the apparatus.

said, flexible surface sections being disposed on said top table surface are in the form of membranes adapted to sag beneath the surface of said table to 7 8 a position controlled by the length of stroke of said I a series of pneumatically-driven shafts for moving shafts; said flat table and urging said flexible surface secand contoured support members attached to said base bemg shaped 9. with the diam-ed {and contour whereby the distances between said conproduct for malntammg control over said flexible membranes as Such membranes fan by gravity toured support members govern the lowest hmlt of neath the top surface of said table. Sag said Sections- 3. An apparatus as claimed in claim 2 including;

tions to sag and conform according to a desired 

1. An apparatus for manufacturing a contoured asbestos cement sheet including; a base, a flat, movable table mounted on said base, said table being formed by a series of alternately rigid and flexible surface sections, a pneumatically-driven piston means adapted to urge horizontal movement of said series of surface sections toward the center of said table upon a given signal; and a series of rigid contoured supports disposed beneath the plane of the top of the surface of said table and so positioned as to permit the nestling of said flexible surface sections within said supports when said flexible surface sections have dropped to their lower most position beneath the surface of said table.
 2. An apparatus as claimed in claim 1 including; a series of shafts driven by pneumatic means urged to move in a horizontal plane towards the center portion of the apparatus. said, flexible surface sections being disposed on said top table surface are in the form of membranes adapted to sag beneath the surface of said table to a position controlled by the length of stroke of said shafts; and contoured support members attached to said base being shaped consistent with the desired end product for maintaining control over said flexible membranes as such membranes fall by gravity beneath the top surface of said table.
 3. An apparatus as claimed in claim 2 including; a series of pneumatically-driven shafts for moving said flat table and urging said flexible surface sections to sag and conform according to a desired contour whereby the distances between said contoured support members govern the lowest limit of sag for said sections. 